The present invention relates to a hoist rope equaliser and is more particularly directed to a system in which an object is to be suspended and moved in a system having a plurality of hoist ropes which connect to the equaliser and the equaliser has a plurality of flexible connection elements such as chains on which the object is mounted. The equaliser has a structure such that load on the respective flexible elements is equalised and the line of action preserved along the direction of elongation of each of the support cables. A particular application of the invention but not necessarily its only application is to a system for use with a dragline having a rigging system which supports and operates a dragline bucket.
Dragline excavators are frequently used to remove overburden to prepare an open-cut coalmining operation. A bucket is provided and capable of scooping a large volume of soil. The bucket is suspended off a long boom with support cables for causing the bucket to be dragged through the overburden, to be filled and then lifted and moved to dump the overburden at a nearby dumping location. Conventionally, the system is as schematically shown in FIGS. 1 and 2 as more particularly described hereinafter and an equaliser is used to equalise the load through left and right support cables.
The capital investment in a dragline is very high and economics dictate that components which are prone to wear can be not only inspected but also be subject of the substitution of replacement parts relatively easily and more important most speedily and safely but in a mining location using relatively simple equipment. However, long working life particularly and readily replaceable components are important. The economic effect of downtime is very significant and needs to be minimised. Accordingly, component design and longevity coupled with superior performance characteristics are desirable. It is paramount that breakdowns and non-scheduled maintenance requirements are eliminated by effective design and good performance parameters.